Dynamic medium switch in co-located plc and rf networks

ABSTRACT

An electronic communication device comprises a first transceiver capable of a bi-directional communication session on a first communication medium; a second transceiver capable of a bi-directional communication session on a second communication medium; and a control logic coupled to the first transceiver and the second transceiver and capable of implementing a convergence layer, wherein the control logic is configured to receive, from the first transceiver, a first signal; and cause, in response to the first signal, data received and transmitted by the first transceiver on the first communication medium as part of a communication session to be received and transmitted instead by the second transceiver on the second communication medium.

CROSS-REFERENCE TO RELATED APPLICATION

The present application is a continuation of U.S. patent applicationSer. No. 14/878,178 filed Oct. 8, 2015, which is a continuation of U.S.patent application Ser. No. 13/553,182 filed Jul. 19, 2012, now U.S.Pat. No. 9,184,779 issued Nov. 10, 2015, which, claims priority to U.S.Provisional Patent Application No. 61/510,584 filed on Jul. 22, 2011,which applications are hereby incorporated herein by reference in theirentireties.

BACKGROUND

Narrow-band power line communication (PLC) transceivers and low-powerradio frequency (RF) transceivers may be used in sensor networks andsmart grid networks. Transceivers are able to transmit and receive data;thus, they may be referred to as bi-directional communication devices.Noise such as wireless local area network (WLAN) transmissions mayinterfere with RF transmissions, and impulsive noises from appliancessuch as washing machines may interfere with PLC transmissions. As PLC,RF, and other technologies proliferate, embedded devices may incorporatea combination of PLC, RF, and other technologies to improve networkconnectivity. For example, some smart meters may incorporate a PLCtransceiver and an 802.15.4 RF transceiver. Because such devices operateon multiple types of networks, they may be referred to as hybriddevices.

SUMMARY

In some embodiments, an electronic communication device is disclosed ascomprising a first transceiver capable of a bi-directional communicationsession on a first communication medium; a second transceiver capable ofa bi-directional communication session on a second communication medium;and a control logic coupled to the first transceiver and the secondtransceiver and capable of implementing a convergence layer, wherein thecontrol logic is configured to receive, from the first transceiver, afirst signal; and cause, in response to the first signal, data to bereceived and transmitted by the first transceiver on the firstcommunication medium as part of a communication session to be receivedand transmitted instead by the second transceiver on the secondcommunication medium.

In other embodiments, a method for electronic communication is disclosedas comprising providing a first transceiver capable of a bi-directionalcommunication session on a first communication medium, a secondtransceiver capable of a bi-directional communication session on asecond communication medium, and a control logic coupled to the firsttransceiver and the second transceiver and capable of implementing aconvergence layer; receiving, by the control logic from the firsttransceiver, a first signal; and causing, by the control logic inresponse to the first signal, data to be received and transmitted by thefirst transceiver on the first communication medium as part of acommunication session to be received and transmitted instead by thesecond transceiver on the second communication medium.

BRIEF DESCRIPTION OF THE DRAWINGS

For a detailed description of exemplary embodiments of the invention,reference will now be made to the accompanying drawings in which:

FIG. 1 shows a system of communication between two electroniccommunication devices;

FIG. 2 shows a system of communication between two electronic devicesaccording to an embodiment of the disclosure; and

FIG. 3 shows a method for electronic communication according to anembodiment of the disclosure.

NOTATION AND NOMENCLATURE

Certain terms are used throughout the following description and claimsto refer to particular system components. As one skilled in the art willappreciate, different companies may refer to a component by differentnames. This document does not intend to distinguish between componentsthat differ in name, but not function. In the following discussion andin the claims, the terms “including” and “comprising” are used in anopen-ended fashion and thus should be interpreted to mean “including,but not limited to . . . .” Also, the terms “couple” and its variationsare intended to mean either an indirect or direct electrical connection;thus, if a first device couples to a second device, that connection maybe through a direct electrical connection or through an indirectelectrical connection via other devices and connections.

DETAILED DESCRIPTION

The following discussion is directed to various embodiments of theinvention. Although one or more of these embodiments may be preferred,the embodiments disclosed should not be interpreted, or otherwise used,as limiting the scope of the disclosure, including the claims. Inaddition, one skilled in the art will understand that the followingdescription has broad application, and the discussion of any embodimentis meant only to be exemplary of that embodiment, and not intended tointimate that the scope of the disclosure, including the claims, islimited to that embodiment.

PLC generally refers to communication of data on a conductor that isalso used to carry alternating current (AC) electrical power, forexample, power lines delivering electrical power at about 110 VAC at 60Hz or about 220 VAC at 50 Hz. PLC communication may be on a power linethat is distributing power at a stepped down voltage to residentialbuildings or within a building such as an office building. In somecases, PLC may not propagate across distribution transformers, forexample across step-down transformers, without some form of signalprocessing to bridge across the two sides or windings of the subjecttransformer. PLC technologies include PoweRline Intelligent MeteringEvolution (PRIME), G3, and Institute of Electrical and ElectronicsEngineers (IEEE) 1901.2. RF communication generally refers tocommunication of data on radio waves in the frequency range of 3 kHz to300 GHz. RF technologies include Zigbee, WLAN of Wi-Fi, and Bluetooth.

FIG. 1 shows a system 100 of communication between two electroniccommunication devices. The system 100 may comprise a PLC transceiver 102and an RF transceiver 104, which may communicate with peer transceiversover time. The PLC transceiver 102 and the RF transceiver 104 may beincorporated into the same device, which may therefore be referred to asa hybrid device. The device may be a smart meter where the PLCtransceiver is a narrow-band PLC transceiver and the RF transceiver isan 802.15.4 RF transceiver. Alternatively, the device may be a deviceother than a smart meter. The system 100 may employ a typical routingprotocol, such as an IPv6 routing protocol for low power and lossynetworks (RPL), for the transceivers 102, 104.

At time 1, the PLC transceiver 102 may initiate a communication sessionover a PLC link 106 with good link quality. Accordingly, the device mayachieve high throughput over the PLC link 106.

The word “link” may be interchanged with the word “medium.” The term“communication session” and its variations may be understood broadly torefer to any ongoing communication between two devices. A communicationsession need not be associated with any particular communication layer,but may instead refer to a communication activity that has duration intime and comprises a plurality of packets that are abstracted as partsof the communication or communication session. A communication sessionmay comprise, for example, a smart meter transmitting a monthly powerusage report in response to a request. The monthly usage report maycomprise usage data and metrics on service quality.

At time 2, an electrical or electromagnetic noise 110 may occur near thesystem 100. If the noise 110 is an impulsive noise from an appliancesuch as a washing machine, then the noise 110 may affect PLCcommunication, but not RF communication. Accordingly, the PLC link 106may exhibit bad link quality, the device may achieve nominal or nothroughput over the PLC link 106, and the communication session maypause.

At time 3, the noise 110 may dissipate, thus restoring the PLC linkquality. With the PLC link quality restored, the routing protocolassociated with the transceivers 102, 104 may therefore choose not toswitch media from the PLC link 106 to the RF link 108, and thecommunication session may resume over the PLC link 106 with highthroughput.

At time 4, the noise 110 may reemerge and once again cause bad linkquality over the PLC link 106. This time, however, the routing protocolmay choose to route the communication session over the RF link 108, butthere may be a lag before the routing protocol can initiate thecommunication session on the RF link 108.

At time 5, the communication session may initiate the communicationsession on the RF link 108. The RF link 108 may, however, exhibit mediumlink quality and low throughput relative to the PLC link 106 throughput.In addition, the routing layer, if left unimpeded, may continue thecommunication session on the RF link 108 for the duration of thecommunication session, in this case until time 13, instead of switchingback to the PLC link 106 as link conditions improve. When performing itsvarious functions, the routing layer may update various routing tablesand therefore consume network bandwidth.

FIG. 2 shows a system of communication 200 between a first electroniccommunication device 202 and a second electronic communication device204 according to an embodiment of the disclosure. The first device 202may comprise a first PLC transceiver 206, a first RF transceiver 208,and a first control module 218. The second device may comprise a secondPLC transceiver 210, a second RF transceiver 212, and a second controlmodule 220. The first PLC transceiver 206, the first RF transceiver 208,and the first control module 218 may be implemented as a singleintegrated circuit or as a system on a chip (SOC). Likewise, the secondPLC transceiver 210, the second RF transceiver 212, and the secondcontrol module 220 may be implemented as a single integrated circuit oras an SOC. Alternatively, the control modules 218, 220 may beimplemented separately from the transceivers 206, 208, 210, 212.

The devices 202, 204 may be referred to as hybrid devices. In anembodiment, the devices 202, 204 may be smart meters where the first PLCtransceiver 206 and the second PLC transceiver 210 are narrow-band PLCtransceivers and the first RF transceiver 208 and the second RFtransceiver 212 are 802.15.4 RF transceivers. Alternatively, the firstdevice 202 may be a smart meter, and the second device 204 may be amonitor or data gathering device that promotes collecting usage reportsfrom a plurality of smart meters and forwarding them to a centralizedprocessing point of a power distribution company. Smart meters typicallyrefer to electrical meters that record information related toconsumption of electric energy. Smart meters typically comprisereal-time or near real-time sensors and provide power outagenotification and power quality monitoring. Smart meters may provide thatinformation to a central system associated with a power provider. Smartmeters may also communicate with each other in high-density populationareas or otherwise using collaborative network technology. The devices202, 204 may comprise transceivers employing other technologies as well.In another embodiment, the devices 202, 204 may not be smart meters, butinstead may be other devices.

The first PLC transceiver 206 and the second PLC transceiver 210 maycommunicate with each other over a PLC link 214. A PLC link may refer tothe power line or conductor itself that provides communication of dataalong with AC electrical power. Likewise, the first RF transceiver 208and the second RF transceiver 212 may communicate with each other overan RF link 216.

The control modules 218, 220 may communicate with their respectivetransceivers 206, 208, 210, 212. The control modules 218, 220 may eachbe executed by a separate processor associated with their respectivedevices 202, 204. The control modules 218, 220 may each monitor,receive, process, and distribute data from their respective transceivers206, 208, 210, 212 and links 214, 216 and may do so through at least onesub-module. The data may relate to received signal strength indication(RSSI), noise level, medium occupation ratio, statistics on packet errorrates with different modulation schemes, and which packets have a validpreamble but an invalid payload cyclic redundancy check (CRC). The datamay enable the control modules 218, 220 to make local decisions such asmedium selection and rate control. When the devices 202, 204 aredescribed below as monitoring, receiving, processing, distributing, orperforming similar functions, it may be understood that they are doingso through their respective control modules 218, 220. The controlmodules 218, 220 may also each cause changes in communication behavioramong their respective transceivers 206, 208, 210, 212 and links 214,216 and may do so through at least one other sub-module. When thedevices 202, 204 are described below as causing changes in communicationbehavior or performing similar functions, it may be understood that theyare doing so through their respective control modules 218, 220. In somecontexts, the control modules 218, 220 may be referred to as controllogic.

The devices 202, 204 may each employ a new protocol layer, a convergencelayer, and may do so through their respective control modules 218, 220.The convergence layer may operate between its respective routing layerand media access control (MAC) layer and thus provide a new protocollayer. In that respect, the convergence layer may filter informationbefore that information reaches its respective routing layers. Theconvergence layer may, for instance, monitor transmission failures anddelays.

The system 200 may initiate a communication session from the firstdevice 202 to the second device 204 across the PLC link 214, butpreferably not across the RF link 216. Under some conditions, the PLClink 214 may support higher throughput and/or a higher communicationrate than the RF link 216. The PLC link 214, when the transceivers 206,210 communicate to and from each other, may be referred to as operatingin a full duplex mode of operation.

The communication session may comprise a series of packet transmissionsfrom the first device 202 to the second device 204 and a series ofacknowledgments from the second device 204 to the first device 202.Alternatively, the communication session may comprise a series of packettransmissions from the second device 204 to the first device 202 and aseries of acknowledgments from the first device 202 to the second device204. Electrical or electromagnetic noise 222 may occur near the system200. As mentioned above, if the noise 222 is an impulsive noise from anappliance such as a washing machine, then the noise 222 may affect PLCcommunication, but not RF communication. If the second device 204 failsto reply with an acknowledgment after a threshold number of packettransmission attempts from the first device 202, and if the RF link 216is available, then the convergence layer associated with the firstdevice 202 may choose to employ the RF link 216 to send a query to thesecond device 204 to determine its link conditions. The convergencelayer may transmit the unsent packet with the query in a singletransmission to the second device 204 over the RF link 216. The seconddevice 204 may then respond over the RF link 216 with informationregarding the link conditions that it is observing. For example, thesecond device 204 may indicate that the noise 222 is too great forpacket transmissions over the PLC link 214. The second device 204 mayobserve and report those link conditions from the second control module220. If the convergence layer does not obtain the requested informationfrom the second device 204 over the RF link 216, then the convergencelayer may wait until a predefined timeout occurs. After the timeout, theconvergence layer may determine that the second device 204 is inoperableor that the RF link 216 is invalid, then provide to its routing layerthat information along with the failed packet itself.

Otherwise, if the information from the second device 204 indicates thatthe noise 222 is merely temporal and that the RF link 216 is anacceptable medium, then the convergence layer may discontinue thecommunication session in the PLC link 214 and initiate a communicationsession in the RF link 216. The communication session in the RF link 216may resume the communication session from the PLC link 214. The system200 may employ a handshake process in order to transition thecommunication session from the PLC link 214 to the RF link 216. Theconvergence layer may place a time limit on the use of the RF link 216for the communication session. After that time limit expires, theconvergence layer may notify its routing layer of any packettransmission failures. If the RF link 216 is also degraded, then theconvergence layer may immediately notify its routing layer of thatdegradation.

If the communication quality improves in the PLC link 214, then theconvergence layer may choose to discontinue the communication session inthe RF link 216 and re-initiate that communication session in the PLClink 214. Once again, the system 200 may employ a handshake process,this time to transition the communication session from the RF link 216to the PLC link 214. The system 200 may prefer to return to the PLC link214 communication due to, for example, a higher throughput in PLCcommunication compared to RF communication.

While a switch from the PLC link 214 to the RF link 216 is describedabove, the system 200 may instead choose to switch from the RF link 216to the PLC link 214, depending on link conditions and other factors. Thesubsequently described embodiments may also permit such linkflexibility. In addition to the dynamic medium switch when onetransceiver is experiencing temporal interference, the system 200 mayemploy both the PLC link 214 and the RF link 216 when one transceiver isexperiencing bursts of traffic loads. When a packet queue size at onetransceiver exceeds a threshold, the system 200 may split trafficbetween the PLC link 214 and the RF link 216. Furthermore, theconvergence layer associated with each device 202, 204 may answerincoming requests from other nodes or devices and provide informationindicating that multiple transceivers belong to their respectivedevices.

Finally, as mentioned above, the first control module 228 and the secondcontrol module 220 may observe and report information to the firstdevice 202 and the second device 204, respectively. That information mayfacilitate proper medium selection. In a first example, if packettransmissions from the first device 202 to the second device 204repeatedly fail, but the noise level and medium occupation ratio are lowacross the medium in use, then it is more likely that the second device204 is experiencing problems, so the convergence layer associated withthe first device 202 may attempt to retrieve information related toconditions at the second device 204. In a second example, if packettransmissions from the first device 202 to the second device 204repeatedly fail, but the noise level across the medium in use is above apredefined threshold, then the second device 204 may report link noiseto the first device 202. In a third example, if the first device 202 issending packets to the second device 204 and if the number of packetswith a valid preamble but an invalid payload CRC is large, then thesecond device 204 may report that a modulation scheme might be tooaggressive. The second device 204 may send a similar report based onpacket error rates with different modulation schemes or based on a lowmedium occupation ratio. In a fourth example, if the first device 202 issending packets to the second device 204 and if there is a high mediumoccupation ratio and a small number of detected preambles, then thesecond device 204 may suggest that line noise or hidden nodetransmissions are causing transmission failures, and the second device204 may suggest that an alternative medium should be used.

FIG. 3 shows a method 300 for electronic communication according to anembodiment of the disclosure. Some actions may be performed in adifferent order from that shown in FIG. 3, and two or more actions maybe performed in parallel rather than serially. At block 302, a systemmay provide a first transceiver capable of a bi-directionalcommunication session on a first communication medium. The system may bethe system 200, the first transceiver capable of a bi-directionalcommunication session may be the first PLC transceiver 206, and thefirst communication medium may be the PLC link 214.

At block 304, the system may provide a second transceiver capable of abi-directional communication session on a second communication medium.The second transceiver may be the first RF transceiver 208, and thesecond communication medium may be the RF link 216.

At block 306, the system may provide a control logic coupled to thefirst transceiver and the second transceiver and capable of implementinga convergence layer. The control logic may be the first control module218.

At block 308, the control logic may receive, from the first transceiver,a first signal.

At block 310, the control logic may cause, in response to the firstsignal, data received and transmitted by the first transceiver on thefirst communication medium as part of a communication session to bereceived and transmitted instead by the second transceiver on the secondcommunication medium.

At block 312, the control logic may receive, from the first transceiveror the second transceiver, a second signal.

At block 314, the control logic may cause, in response to the secondsignal, data received and transmitted by the second transceiver on thesecond communication medium to be received and transmitted instead bythe first transceiver on the first communication medium.

Certain features that are described in the context of separateembodiments can also be combined and implemented as a single embodiment.Conversely, various features that are described in the context of asingle embodiment can also be implemented in multiple embodimentsseparately or in any suitable subcombinations. Moreover, althoughfeatures may be described as acting in certain combinations and eveninitially claimed as such, one or more features from a combination asdescribed or a claimed combination can in certain cases be excluded fromthe combination, and the claimed combination may be directed to asubcombination or variation of a subcombination. Although variousaspects of the invention are set out in the independent claims, otheraspects of the invention comprise other combinations of features fromthe embodiments and/or from the dependent claims with the features ofthe independent claims, and not solely the combinations explicitly setout in the claims. Certain functions that are described in thisspecification may be performed in a different order and/or concurrentlywith each other. Furthermore, if desired, one or more of theabove-described functions may be optional or may be combined.

The above discussion is meant to be illustrative of the principles andvarious embodiments of the present invention. Numerous variations andmodifications will become apparent to those skilled in the art once theabove disclosure is fully appreciated. It is intended that the followingclaims be interpreted to embrace all such variations and modifications.

What is claimed is:
 1. A device comprising: a first transceiverconfigured to receive a first signal indicating a quality of a firstcommunication medium; a second transceiver configured to receive asecond signal indicating a quality of a second communication medium; anda processor coupled to the first transceiver and to the secondtransceiver, the processor configured to obtain data; select, inaccordance with the first signal and the second signal, the firsttransceiver or the second transceiver, to be a selected transceiver; andinstruct the selected transceiver to transmit the data over a selectedcommunication medium.
 2. The device of claim 1, wherein the firstcommunication medium is a power line communication (PLC) medium, thefirst transceiver is a PLC transceiver, the second communication mediumis a wireless medium, and the second transceiver is a wirelesstransceiver.
 3. The device of claim 1, wherein the device is a firstdevice and the selected transceiver is configured to transmit the datato a second device.
 4. The device of claim 1, wherein the firsttransceiver is further configured to receive a third signal indicating aquality of the first communication medium, the second transceiver isfurther configured to receive a fourth signal indicating the quality ofthe second communication medium, and the processor is further configuredto switch the selected transceiver in accordance with the third signaland the fourth signal.
 5. The device of claim 1, wherein the firstsignal comprises a received signal strength indicator (RSSI) of thefirst communication medium.
 6. The device of claim 1, wherein the firstsignal comprises a noise level of the first communication medium or amedium occupation ratio of the first communication medium.
 7. The deviceof claim 1, wherein the first signal comprises statistics on packeterror rates with different modulation schemes for the firstcommunication medium or a number of packets having valid preambles andinvalid payload cyclic redundancy checks (CRCs).
 8. The device of claim1, wherein the first transceiver is further configured to transmit apacket, and the first signal is a lack of an acknowledgment responsiveto the packet.
 9. The device of claim 1, wherein the first transceiver,the second transceiver, and the processor are in a system on a chip. 10.The device of claim 1, wherein the device is a smart meter.
 11. A methodcomprising: receiving, by a first transceiver, a first signal indicatinga quality of a first communication medium; receiving, by a secondtransceiver, a second signal indicating a quality of a secondcommunication medium; obtaining, by a processor, data; selecting, by theprocessor, in accordance with the first signal and the second signal,the first transceiver or the second transceiver, to be a selectedtransceiver; and instructing, by the processor, the selected transceiverto transmit the data over a selected communication medium.
 12. Themethod of claim 11, wherein the first communication medium is a powerline communication (PLC) medium, the first transceiver is a PLCtransceiver, the second communication medium is a wireless medium, andthe second transceiver is a wireless transceiver.
 13. The method ofclaim 11, further comprising transmitting, by the first device, the datato a second device.
 14. The method of claim 11, further comprising:receiving, by the first transceiver, a third signal indicating a qualityof the first communication medium; receiving, by the second transceiver,a fourth signal indicating the quality of the second communicationmedium; and switching, by the processor, the selected transceiver inaccordance with the third signal and the fourth signal.
 15. The methodof claim 11, wherein the first signal comprises a received signalstrength indicator (RSSI) of the first communication medium.
 16. Themethod of claim 11, wherein the first signal comprises a noise level ofthe first communication medium or a medium occupation ratio of the firstcommunication medium.
 17. The method of claim 1, wherein the firstsignal comprises statistics on packet error rates with differentmodulation schemes for the first communication medium or a number ofpackets having valid preambles and invalid payload cyclic redundancychecks (CRCs).
 18. The method of claim 1, further comprisingtransmitting, by the first transceiver, a packet, and the first signalis a lack of an acknowledgment responsive to the packet.
 19. The methodof claim 11, wherein the first transceiver, the second transceiver, andthe processor are in a system on a chip.
 20. The method of claim 11,wherein the device is a smart meter.